1. Field of the Invention
The present invention relates to an apparatus for inspecting a bump junction of a semiconductor element and a substrate in a flip chip for performing inverted mounting on a substrate made of organic or ceramic matter through a bump or the like and a method of inspecting the same.
2. Description of the Related Art
In a flip chip which is attracting attention recently in advancing high density mounting, ball shaped metals or the like called bumps 2 are connected by soldering or the like to electrodes 17 of a plurality of bare chips 1 arranged evenly as shown in FIG. 1. These fitted bumps 2 are connected also by soldering or the like to electrodes 18 of a substrate made of an organic or ceramic matter or the like.
Since such a flip chip has a connecting portion with the substrate on the back of the bare chips 1 for the purpose of executing high density mounting, it has such a disadvantage in point of inspection that the connecting portion cannot be seen directly as against that the connecting portion was located at a position that could be seen directly in a conventional surface mount device (SMD) component.
Therefore, such a method that it is confirmed for the substrate in which flip chips are used whether connection has been made nicely by applying a current to the bare chip 1 and confirming the operation without inspecting the connection has been adopted at a stage of trial manufacture, but such an inspection method is not suitable for mass production. Further, in such a test with turning on electricity, the bare chip 1 is operated when an electric current is turned on under any circumstances of the connecting portion. Therefore, even when a large void has been generated at a portion where the bump 2 has been connected by soldering for example, judgement is made to be an excellent article since there is no problem electrically and sufficient connection inspection cannot be made in such a case, thus producing a reliability problem.
As a result, an apparatus for inspecting a connecting portion in bare chip mounting becomes necessary. In an apparatus for inspecting a solder junction portion of a semiconductor device shown in FIG. 2 (Patent Laid-Open No. HEI4-359447), it has been tried to make the junction portion of the bump 2 between a substrate 18 and a bare chip 17 visible by utilizing transmission of X-rays. In this apparatus, however, X-rays are radiated from right above the connecting portion so as to measure a shadow thereof. Therefore, an X-ray source has to be brought to right above the connecting portion, and the X-ray source has to be moved to right above of individual bump 2 at the connecting portion of the substrate 18 where a plurality of bumps 2 are arranged in flip chip mounting. Further, since the connecting portion cannot be visually observed directly, it is also difficult to move the X-ray source to right above the connecting portion. Furthermore, the X-ray source is expensive, and consideration for a human body also becomes necessary concerning the use thereof.
A flip chip which is presently focused with the spotlight of attention is a mounting method which has been developed for the purpose of executing high density mounting, but it is a mounting construction in which the junction portion between the bare chip and the substrate cannot be visually observed directly because high density mounting is performed. Therefore, a conventional inspection apparatus of a type used for an SMD component or the like is not applicable to the connection inspection of flip chip mounting in which the junction portion cannot be observed directly.
Further, although that which utilizes an X-ray apparatus has been invented as an inspection apparatus for flip chips, there have been extremely difficult problems in such points that not only there are difficult points in point of mechanism such as arrangement and movement of an X-ray source for inspection, but also consideration for a human body is required thus making products expensive.
As described above, since there has been heretofore no suitable inspection apparatus for flip chips, it is foreseen that yield of flip chips is deteriorated, and future progress or realizability of high density mounting by flip chips is apprehended due to cost increase.
Therefore, a non-contact inspection apparatus and inspection method that can be used preferably for such flip chips and are provided with sufficient inspection performance suitable for mass production of semiconductor devices have been desired.